U.S. Pat. No. 6,889,637 discloses a two-stroke engine having a cylinder which is connected to an air filter via an air channel and a mixture channel. The air channel and the mixture channel are guided in common in a carburetor and are separated from each other by a partition wall. During operation of the two-stroke engine, pressure waves develop in the channels because of the opening and closing of the air channel and the mixture channel. Especially during full load operation of the two-stroke engine, a complete separation of the air channel and mixture channel is wanted. It can, however, occur that fuel is drawn by suction from the mixture channel into the air channel because of an underpressure in the air channel as a consequence of leaks, especially, in the area of the partition wall. The air, which is conducted through the air channel to the cylinder, is used for scavenging the combustion chamber. Fuel drawn by suction into the intake channel can therefore escape uncombusted through the outlet. In this way, the exhaust-gas values of the two-stroke engine deteriorate. A complete sealing of the partition wall is only possible with a high constructive complexity.
It has been shown that during operation of the two-stroke engine, the fuel discharge from the fuel opening into the mixture channel can be deteriorated by pressure waves formed in the mixture channel. The deteriorated fuel discharge through the fuel opening can lead to an uneven running of the two-stroke engine and to a deteriorated acceleration performance.